* { box-sizing: border-box; }

body {
  margin: 0;
  padding: 24px;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: #f4f5fb;
  color: #111827;
  display: flex;
  justify-content: center;
}

.app {
  width: 100%;
  max-width: 1600px;
  position: relative;
  padding: 18px 0 22px;
  background: transparent;
  box-shadow: none;
}

header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 8px;
  margin-bottom: 12px;
}

.title-row { display: inline-flex; align-items: center; gap: 6px; }

h1 {
  margin: 0;
  font-size: 1.35rem;
  font-weight: 600;
  letter-spacing: 0.03em;
  text-transform: uppercase;
}

.icon-btn {
  width: 24px;
  height: 24px;
  border-radius: 999px;
  border: 1px solid #d1d5db;
  background: #f9fafb;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  padding: 0;
  font-size: 0.78rem;
  color: #6b7280;
  transition: background 0.1s ease, box-shadow 0.1s ease, transform 0.1s ease;
}
.icon-btn:hover {
  background: #e5e7eb;
  box-shadow: 0 2px 6px rgba(148, 163, 184, 0.6);
  transform: translateY(-1px);
}

.layout {
  display: grid;
  grid-template-columns: minmax(0, 1.6fr) minmax(0, 1.2fr) minmax(0, 1.2fr);
  gap: 12px;
}

.left-column-box {
  background: #ffffff;
  border-radius: 18px;
  padding: 18px 20px 22px;
  box-shadow:
    0 20px 40px rgba(15, 23, 42, 0.08),
    0 0 0 1px rgba(148, 163, 184, 0.2);
  align-self: start;
  position: sticky;
  top: 54px;
}

@media (max-width: 780px) {
  .layout { grid-template-columns: minmax(0, 1fr); }
  .left-column-box { position: static; top: auto; }
}

.card {
  border-radius: 14px;
  padding: 12px;
  border: 1px solid #e5e7eb;
  background: #f9fafb;
}
.card-title {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 8px;
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.07em;
  color: #6b7280;
}

button {
  border-radius: 999px;
  border: 1px solid transparent;
  padding: 6px 14px;
  font-size: 0.8rem;
  font-weight: 500;
  background: #111827;
  color: #f9fafb;
  cursor: pointer;
  transition: transform 0.07s ease, box-shadow 0.07s ease, opacity 0.15s ease;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 4px;
  white-space: nowrap;
}
button.secondary { background: #f3f4f6; color: #111827; border-color: #d1d5db; }
button.small { padding: 4px 10px; font-size: 0.75rem; }
button:disabled { opacity: 0.35; cursor: default; transform: none; box-shadow: none; }
button:not(:disabled):hover { transform: translateY(-1px); box-shadow: 0 10px 20px rgba(148,163,184,0.4); }

.buttons-row { display:flex; flex-wrap:wrap; gap:6px; align-items:center; margin:8px 0 6px; }

/* Start Solving (green) / Restart Mix (red) */
.btn-start-solve {
  background: #16a34a !important; /* green */
  color: #ffffff !important;
  border-color: #16a34a !important;
}
.btn-start-solve:not(:disabled):hover {
  background: #15803d !important; /* darker green */
  box-shadow: none !important; /* no glow, just color change */
}

.btn-restart-mix {
  background: #dc2626 !important; /* red */
  color: #ffffff !important;
  border-color: #dc2626 !important;
}
.btn-restart-mix:not(:disabled):hover {
  background: #b91c1c !important; /* darker red */
  box-shadow: none !important; /* no glow, just color change */
}